Yaybu

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- Fix default verbosity to not be debug mode

- Use context log features of latest yay version to provide better error
messages when yay parsing fails. These are only shown when verbosity is at
debug level.

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- Fix etag request headers so that etags can be back from a yaybu running in
remote mode.

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- Fix etag registry to actually store etags

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- Now depends on yay >= 0.0.53 to support etags (which reduces the amount of
network traffic when files haven't changed) and to support fetching of
cookbooks packaged as python eggs from code repositories.

- Fix logging typos

- If there is a ~/.yaybu/defaults.yay or ~/.yaybu/defaults.yay.gpg
it will be loaded.

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- Fix simulate error

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- Generate proper exceptions when trying to lookup users and groups that don't
exist.

- Refactor 'passthru' commands as 'inert' commands as it better reflects the
intention.

- Remove 'exceptions' option from shell.execute

- 63 Simulate fails on Execute when user missing from /etc/passwd. Code
refactored to work around this.

- Experimental Paramiko support.